The first thing you hear people say to newcomers is that you need to learn and understand the basics. To explain them to you now would take alot of time (that I sadly don't have) and people before me have done it better than I could ever do. Just type 'basics' in the search bar and you'll find alot of helpfull links. :)

You also asked about white magic and by that you mean 'good' magic. Remember that magic is magic and that it isn't good or bad by itself. That depends on how you use it.

Also remember that alot of the 'white' magic spells are fake, magic can't do impossible things like beeing pregnant without etc. Just use common sence and you'll easily figure out what's real and fake. :)

The last advice I'll share with you is that if you ever decide to cast a spell, create your own. It will make it more personal and thus more powerfull.